#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>
using namespace std;
const int N = 1e4 + 10;
int n, m;
int f[N][N];
int a[N][N];
int main()
{
    cin >> n >> m;
    while (n--)
    {
        int x, y, v;
        cin >> x >> y >> v;
        x++;
        y++;
        a[x][y] += v;
    }
    n = 5001;
    for (int i = 1; i <= n; i++)
    {
        for (int j = 1; j <= n; j++)
        {
            f[i][j] = f[i - 1][j] + f[i][j - 1] - f[i - 1][j - 1] + a[i][j];
        }
    }
    int ret = 0;
    m = min(m, n);
    for (int i = m; i <= n; i++)
    {
        for (int j = m; j <= n; j++)
        {
            int i1 = i - m + 1;
            int j1 = j - m + 1;
            ret = max(ret, f[i][j] - f[i1 - 1][j] - f[i][j1 - 1] + f[i1 - 1][j1 - 1]);
        }
    }
    cout << ret;
    return 0;
}